In the Feb. 16 SN: Robots roll into the classroom, brain zaps for severe depression, particle colliders of the future, how to walk like a tetrapod, sleepless nights boost Alzheimer's proteins and more.

Some fungi species, including certain mushrooms, sop up radioactive elements from dirt. The 1986 Chernobyl disaster contaminated large swaths of European soils with cesium-137 and prompted concerns that truffles could become radioactive.

The work provides an all clear for Burgundy truffle hunters and connoisseurs around the world, the researchers write. While not radioactive, at more than $400 per kilogram, Burgundy truffles still may not be safe for the pocketbook.